Art of cracking and coking hydrocarbon oils



Nov. 10, 1931. H. PELZER l ART OF CRACKING AND COKING' HYDROCARBON OILS Filed Feb. 18, 1929 INVENTOR /larr/L, Pelzer' ATTORNEYS mmv All

E Sw@ Patented Nov.l 10, 1931 UNITED STATES PATENT ori-Ica HARRY PmlZER, OF HIGHLAND, INDIANA, ASSIGNOR TO SIN CLAIR REFINING GOM- PANY, OF NEW YORK, N. Y., A CORPORATION F MAINE amor CRACKING AND COKINGYDROCARBON oILs Application led February 18, 1929. *Serial No. 340,996.

This invention relates to improvements' in the combined vapor phase cracking of oils,

such as gasoil or kerosene stocks, for the production of lower boiling oils, such as gasoline, and the coking of heavy oils7 such as crud-es, topped crudes, flux oils, other residual oils and the like. The combined operation of the invention is of special application in the handling of crude stocks or residual stocks the handling of which usually involves difliculties due to corrosion or the products of whichare unusually refractory with respect to the usual refining operations, because of the character or quantity of sul, phur compounds in the stock, for example; b ut, as Will appear, `the invention is, in certain aspects, of more general application.

According to this invention, the hot vapor mixture from a vapor phase cracking operation, while still at` high temperature, is

passed in intimate contact .with a liquid oil mixture to be reduced to coke in a receptacle, a horizontal or vertical drum forexample, adapted to recelve an accumulating charge of coke and this liquid oil mixture is coked in this receptacle by the.

heat of the hot vapor mixture from the vapor phase cracking operation, the hot vapor mixture from the coking receptacle, including vapors formed in the coking operation as well as vapors from the vapor phase cracking operation, is discharged into andbeneath the surface of a liquidbody of oil in a separate receptacle, a drum with provision for the maintenance of this liquid body for example, the stock to be reduced to coke is supplied to this liquid body in the separate receptacle, and the oil mixture, constit'uting the liquid body in the separate receptacle, is supplied from th'elseparate receptacle to the coking receptacle there to'be u reduced to coke. rlhe vapor mixture from Athe separate receptacle, including vapors from 'the vapor.` phase cracking operation, vapors formed the coking operation and any'vapors separated from the-l-.stocksupplied to the liquid body therein, iszglischarged to suitablel condensing orfractionating and condensing' or other recovery. apparatus., The coke product formed in the coking receptacle portant so lon coking operation is promoted by maintaining intimate and distributed contact between the hot vapor mixture from the vapor phase cracking operation and the stock to be reduced to coke in the coking receptacle; the hot vapor mixture may be introduced into the coking receptacle in line streams at a number of points or the stock may be sprayed into the coking receptacle or both of these expediente may be utilized, for example. The maintenance of the necessary intimate contact between vapors and liquid in the coking operation, however, involves entrainment in the vapor mixture discharged from the coking receptacle of oil or tarry material, apparently in mist-like orm. Such entralned material is separated fromthe hot vapor mixture discharged from the coking receptacle in the 'scrubbing operation to which this vapor mixture is subjected in the liquid oil body inta which it is-discharged. This scrubbing operation is promoted by maintaining the liquid body at a temperature not exceeding 800o F., or better 7 50 F. By supplying the stock to be coked to this liquid ody, this stock is preheated before introduction into the coking receptacle'and it is also made to serve, in an advantageous way, as a scrubbing medium for the separation of entrained material from the hot vapor mixture discharged from the coking receptacle and as a medium for returning such separated entrained materialV to the coking receptacle. Referring to the vapor phase cracking operation proper, the apparatus or the precise u mannerin which it is carried out is not imas the hot products of the operation are ischargeditherefrom at temperatures upwards of 950-1050"` F. The coking operation, however, may be promoted by supplying a charging stock of limited b011- ving range to the vapor phase cracking operation; the'charging stock supplied to the vapor phase cracking operation in the coinbined operation of the invention is, with advantage, a stock 'of which 70% boils oli within a range not substantially exceeding F. under atmospheric pressure.

The invention will be further described in connection with the accompanying drawing which illustrates, diagrammatically and conventionally, one form of apparatus, in elevation and partly in section with parts broken away, adapted for carrying out the invention, but it is intended and will be understood that the invention can be carried out in other and dierent forms of apparatus and that this further description is intended as exempliication of the invention..

oil mixture is thereby coked in receptacle 2,

the hot vapor mixture from the coking receptacle 2 is discharged into and beneath the surface of the liquid body of o il maintained in the lower end of tower 3, the voil to be reduced to coke issupplied to this liquid oil body through connection 6, the. resulting liquid oil mixture is supplied from this liquid body to the coking receptacle 2, as noted, the resulting vapor mixture is discharged from the upper end oftower 3 through connection 7, and the coke product is periodically discharged from the coking receptacle 2.

The vapor phase cracking operation proper may be carried out, for example, as described in application Serial No.- 198,621,7liled. June 13, 1927, by me, and the hot vapor mixture from the digesting drums discharged directly into the coking receptacle, or'the digesting drums may b omitted and the hot vapor mixture from the heater proper discharged directly into the coking receptacle. In the combined operation of the invention, the c oking operation subjects the. hot vapor mixture from the vapor phase cracking operation to what might be termed a period of digestion. In the apparatus illustrated, the vapor phase 'cracking operation proper is carried out in the heater 1 comprising two groups of series V"connected heatingtubes arranged in the heatcounter-current ing flue ory a furnace 48, the oibflow-ing firstA through one of the oups of heating tubes to t e-cooler heating gases 7 and then through the other group of heating through the heating flue,

tubes concurrent to the hotter heating gases, a fan 9 for circulating with dampers as shown for recirculating'partto the stack 11, a fan 12 and a preheateri13 arranged in the stack 11 for supp-lying pre-` heated air for combustion to the rebox 14 of the furnace 8. Oil is supplied to the heater 1 through connection 15 and the hot oil products of the vapor phase cracking operation' carried out therein are discharged through connection 16. i

The coking operation proper may be carried out, for example, in a horizontal or vertical drum with suitable means, removable heads or the'like, for the discharge of the coke product `formed and deposited in the coking receptacle. In general, a vertical coking drum is more easily cleaned and a horizontal coking drum, excepting for special operating conditions, yields denser and more coherent coke. For example, the coking operation may be carried out in a drum 5 in diameter and 20 high (vertically arranged) or in a drum 9 in diameter and 30 long (horizontally arranged) in the vertical drum the hot vapor mixture from the vapor' phase cracking op'- eratioii may be introduced through a single inlet or through anumber of inlets in the bottom or in the side Walls near the bottom and in the horizontal drum the hot vapor mixture from the vapor phase cracking operationvmay l be introduced through 1% holes 011,18 ceni ters in the lower side of a 1 pipe arranged longitudinally and near the bottom of the drum. In the apparatus illustrated, the coking operation proper is carried out in l"the drum 2. The hot vapor mixture from the heater 1 is discharged int the lower end of the coking drum through connections 16 and 17 and the hot vapor mixture from the coking operationis discharged from the upper .lll

end of the coking drum through connection er heads of the coking drum. The oil mix ture to be coked is sprayed-into the top of the coking drum through connection 4.

Connections 20, 21 and 22 are provided for supplying steam to the heater 1, the lower Vend of the coking drum 2 and the lower end of the scrubbing tower 3, respectively, and condenser 23 is provided for use when steam# ing out the coking drum 2. Steam may be suppliedto the heater 1 during the initialv period of operation or. during regular operation. Steam may be supplied to the coking drum 2 during the initial' period of operation, for example to assist in heating the coking drumto operating temperatures, durcing regular operation, or during the final y the heating vgases period ofoperation, for example to assist in ducts 10 provided drying the coke product. Steam may be supplied to the scrubbing tower 3 during the initial period of operation or during regular operation, for example to assist in stripping the oil mixture constituting the liquid body .in the lower end of the scrubbing tower of vaporiza-ble constituents.

The scrubbing operation proper may be carried out, in any suitable receptacle providing for the maintenance of a liquid body of oil and for the discharge of the hot vapor mixture from' the coking operation into and beneath the surface of this liquid body so as to subject the hot vapor mixture to a thorough scrubbing. Means for refluxing very high boiling constituents of the vapor mixture escaping from the liquid oil body in 4the scrubbing operation to this liquid oil body, as in the apparatus illustrated, may be provided with advantage but are not essential. vIn the apparatus illustrated, the scrubbing operation proper is carried out in the scrubbing tower 3. The hot vapor mixturefrom the coking drum 2 is introduced into and beneath the surface of a liquid body of oil maintained in the lower end of this scrubbing tower through a normally submerged K inlet connection 24. The oil stock to be reduced to coke is supplied to this liquid bodyr through connection 6 and the resulting oil mixture is discharged through connection 25, the rates of supply and discharge being regulated to maintain the necessar)7 liquid body. For example, a sulicient liquid body may be maintained in the lower end of tower 3 to submerge the end of the inlet connection 4 or thereabout. The liquid oil mixture to be coked is pumped from the liquid body in the lower end of tower 3 through connection 4 by means of hot-oil pump 5 into the coking drum. The particular type of hot-oil pump illustrated,-that designated 5 and also that designated 26, is described in more detail in application Serial No. 197,209, filed J une-7 1927 ,by Thomas de C. Tift. Any excess of this oil mixture Vis discharged through connection 27 and cooler 28' to storage. In the scrubbing apparatus illustrated, a number of fractionating baies or plates .are arranged in the upper part of the tower 3. Control yofthe scrubbing operatiomcarried out in,`

this towervmay be supplemented by the regulated introduction, through connection 29, of asuitable" refluxing.,medium.`l For exsequently condensed in the operation maybe supplied to the upper endof tower 3 throughV connections 30, 31 or32, connection 33 and" connection 29 j by means of pump 34 as" a refluxing med1um or asimilar oil fraction from some other lsource may be supplied through connection 35 as arefluxing medium.

In the apparatus illustrated, fractionating towen39 is provided for the separation of.,v

one or two rintermediate oil ,tractions, it desired, and fractionating tower 40 ispro-vided v of these means.

for the separation or preparation of a charging stock for the vapor phase cracking operation, if desired, or for the direct production of a distillate product, gasoline for example, of the desired boiling range, if desired. Each of the towers 39 and 40 are provided with a' number of fractionating bailles or plates; these towers may, for example, be of conventional bubble tower construction. Condensate is discharged from tower 40 through connection 41, and condensate is discharged froml tower 39 through connection 42, oran additional condensa-te fraction may also be discharged from tower 39 from an intermediate point through connection 43. The vapor mixture escaping from the upper end'of the vscrubbing tower 3 isintroduced either into v lowermost part of the tower through connection 47 or into the tower at an intermediate point in the lower part through connection 48 to provide for stripping of the condensate separated in this fractionating tower. A,.

pair of reflux condensers, 50 and 5l, 52 and 53, are provlded in connection withy frac-tionating towers 39 and 40, respectively, to provide control of the fractionating operations carried out in these towers. These frac-tionatinef operations may be controlled by regulated reluxing of the vapor mixtures escaping through these reflux condensers. or bv the regulated introduction of reiuxing media through Aconnectlo-ns 49 and v54, or by both tra-neous cooling medium may he used to control condensation in refiux conc ensers 5l and Water or some other ex- 53, supplied through connection 55 and' disf chargedv through connection 56. The oil to be reducedtorcoke. for example, or part of it, may be used to control condensation in reflux condensers 50`and 52, supplied'through cony .nection 57, and discharged through connecample, a part of one or more oil fractionssubtion 58. such oil at the same time thereby belng preheated.. Either or both an extraneous bothot the redux Wcondensers-5l and 53 are used, the .extranebnscooling medium may7 be passed through them in parallel or first through 53 and then through 51 bvmeans oftheeonnectionsshown, and similarly, when both of the reuxcondensers 50 and 52are vg used, the'stockcooling medium maybe passed through them in parallel or irst through 52 and then through 50. A part of one or more oil fractions condensed in tower 39 or in tower 40 may beA supplied to the upper end of tower 39 through connections 30, 31 or 32, connection 36 and connection 49h51 means of pump 37 as a reiiuxing medium, or a similar oil fraction from some other source may be supplied through connection 38 as a reuxing medium. A part of the distillate product may be supplied to the upper end of tower 40 through connections 59 and 54 by means of pump as a refluxing medium, or a similar oil fraction from some other source refluxing medium.` Any condensate or vcondensates discharged from ractionating tower 39 not returned as a reiiuxing medium, and any condensate discharged from fractionating tower 40, either before or after passing through heat exchanger 62, not returned as a refluxing medium or not supplied to the vapor .phase cracking operation, are discharged through coolers 63, 64 and 65 and connections 66, 67 and 68 to storage.

In the apparatus "illustrated, the vapor mixture escaping from the 'fractionating tower 40 through connection 69 is discharged to the condenser 70, either directly through connection 71 or through the refining tower 72 through connections 73 and 74. When the refining tower 72 is included in the operation,.

the vapor mixture may be subjected to refinf ving treatment therein, for example by passage through an adsorptive catalyst such as fullers earth. High boiling material sepa:

rated in the reinii'ig tower, polymers pro-p,

duced by the action of an adsorptive catalyst for example, may be discharged through connection 75 or returned to the operation,

throughfconnection 7 6,' with the stock to be coked. The condenser 70 is arranged to dischargeinto receiver and separator 77. Condensate is discharged from receiver 77 through connections 78 and 79 and uncondensed vapors and gases are discharged 'throughconnection 80.

In the apparatus illustrated, the charging stock supplied to the vapor phase cracking operation through connection 15 may coinprise either a raw stock supplied through connection 81 by means of pump 82, or a con- 'densate from tower .40 or a condensate mixture from tower 40 including unvapori'zed constituents of a refiuxing medium introducedthurough connection 54 or connections,`

54 and,61 (supplied through connection 83 by means offpump 26) or a condensate or cono densate mixture from tower 40 together with A or afinixtii'reofI any' twofor inorefofthe foregoing'. All or pat'igofth'e condensate or'con' a raw stock supp-lied through connection 84,

i i densatei'mixture discharged through connec- A Y v 6 tin'fl, oi-.allpr part of the condensate or con- 5 densate mixture discharged.throughzeonnecl may be supplied through connection 61 as a`y tion 41 and supplied to the vapor phase cracking operation, `.may be passed through the heat exchanger. 62.

In the apparatus illustrated, the oil stock to be reduced to coke supplied to the liquid oil body in the lower end of tower 3 and thence to thecoking drum 2 may either be supplied, or in part supplied, to this liquid oil body directly through connections 85, 86, 87, 88 and ,6 by means of pump 89, or be supplied, or in part supplied, through connection 86, heat exchanger 62 and connections 90, 88 and 6, or be supplied, or in part supplied, through connections 86, 87 and 57, either or both reflux condensers 50 and 52 and connections 58 and 6, or be supplied, or in part supplied, through connection 8 6, heat'exchanger 62, connections 90 and 57, either or b oth redux condensers 50 and 52 and connections 58 and 6, or through any two or more of'tliese paths. To the extent that this stock 1s passed through heat exchanger 62 or reflux condensers 50 and 52, it is thereby preheated.

In the apparatus illustrated, the coking drum 2, the towers 3, 39 and 40, the vapor lines between them and between the heater 1 and the coking drum, the connections 41 and 83, the connections 25 and 4 and the connections 90, 88, 57 58 and 6 are, with advantage, lagged or thermally insulated. A specific example of an operation embodving the invention ascarried out in apparatus of the type illustrated will further exemphfy the invention: Fires are started and the heating furnace 8 is brought to operating temperatures while circulating steam through the heater 1 and the coking drum 2. When the coking drum temperature reaches about-300 F., the circulation of gas oil instead of steam through the heater 1 is er until suicient condensate has accumulated in tower 40 to supply the heater from this source. When the circulation of oil through the heater is started, topped crude is pumped into the lower end of tower 3 through connection 6 at a'ratel regulated to maintain the temperature of the liquid body therein in the neighborhood of 7000/1?. The resulting oil ,mixtureis pumped from the lower end of tower 3 at \a rate regulated to maintain a liquid oil body therein submerging the inlet connection 24 the desired depth; this oil mixture is pumped to storage untilthe system has `reached uniform operating conditions and it is then pumped into the coking drum 2 through connection 4. During regular operation, the furnace operation is regulated so that the hot vapor mixture from the `vapor phase cracking operation is discharged `throughconnectionv 16 at a temperature in the neighborhood of 11001-1120", F., the temperature .ofthe liquid body inthe lower ,end oftewel: 3*,is`maintaind in the neighborhood Aof 700 F., and the temperature of the vapor started; a raw gas oil is supplied to the heat-x '66 stock supplied tothe .vaporphase cracking` mixture discharged from the coking drum into this liquid body may approximate 900- 1000 F. The topped crude supplied to the liquid body in the lower end of tower 3. through connection 6 is passed through the heat exchanger 62 and then through reflux condenser 5() on its way to thisl liquid body. N o other refluxing medium, direct orlindirect is used in tower 39. Heavy gas oil, a condensate from tower 39 for example, is supplied to the uper end of tower 3 at a rate regulated to maintain the vapor mixture'escaping through connection 7 ata temperature in the neighborhood of 700 F. The condensate or condensates from tower 39, ex-

cepting such as is supplied to the upper end..Z

of tower 3 as a refluxing medium, is pumped to storage. Water is circulated through` reflux condenser 53 at a rate regulated to maintain the vapor mixturey escaping through connections 69 and 71 directly to condenser 7 0 such that not less than 90% of. the resulting distillate product'boils off up to 392 F.'under atmospheric pressure. The condensate from 'tower 40, together with light gas oil supplied through connection 84 at a rate regulated to maintain a substantially constant *Y volume of condensate in the lower` end of tower 40, is pumped through the heater 1. en a charge of coke has accumulated in the cokingv drum 2, the oil mixture from the liquid bodyin the lower en d of tower Bis again pumped to storage instead of to the 'coking drum. The hot vapormixture from the heater 1 is passed through the heater for a further period long enough to insure drying of the coke product, 8 hours for example, and this vapor mixture is then by-passed to the tower 3, the coking drum being then( steamed out and the charge of coke removed. As soon as the coking drum has been` cleaned,

" it is out back in again and the coking operation is resumed.,

e A tar resulting from a cracking operation, a pressure cracking still tar for example, may, with advantage, be mixed with the stock to be reduced to coke and' this mix- `ture supplied to theopera'tion, yas described in application Serial No. 345892f1ed March 9, 1929, by .George R. Lord. However, in carry-' ing out this invention, some tar produced in the vapor phase crackingoperation is separated from the hot vapor mixture subjected ,to the scrubbing operation in the oil mixture supplied to the coking operation and, probably. some tar produced in the vapor phase cracking-operation is separated yfrom the hot vapor mixture in the coking operation itself.

f In carrying out the present inventiomthe operation proper may consist' exclusively of,

lor maycomprise in large part oil composeparated from the vapo` mixture including the vapors of the desired distillate product,

-for example by condensation in tower 40 in the` apparatus illustrated, before condensation of the distillate product. 1 I claim:

1. In a combined oil vapor phase cracking and coking operation, the improvement which comprises vaporizing and cracking oil in the `vapor phase, passing the hot Vapor mixture liquid oil mixture in the said separate coking receptacle, discharging a vapor mixfrom the liquid body Vture from the said separate receptacle and periodically discharging a coke product from the said coking receptacle. 0 In a combined o il vapor phase crackin and coking operation, the improvement which comprises vaporizing and cracking oil inthe vapor phase passing the hot vapor mixture from the vapor phase cracking operation, before the' temperature .of the said vapor mixture falls below 1050 F., in intimateI contact with a heavy hydrocarbon liquid oil mixture to be reduced to coke in a receptacle adapted to receive an accumulating charge of coke and thereby coking said oil mixture in said receptacle, discharging the hot vapor mixture from the said coking receptacle into and beneath the surface of a liquid body of oil in a separate receptacle, supplying the oil to be' reduced to coke to the said liquid body in the said separate receptacle and supplying the resulting liquid oil mixture from the liquid body in the said separate receptacle'to the said coking receptacle, discharging a vapor mixture from the said separate receptacle and periodically discharging a coke product from the said coking, receptacle.

3. In a combined oil vapor phase cracking and coking operation, the improvement which comprises vaporizing and cracking oil in the vapor phase .passing the hot vapor mixture from the vapor phase cracking operation, before.,thetemperature of the saidv vapor mixture'falls below 950 F., in intimate contact' with' a heavyhydrocarbon liquid oil mixtureto be reduced to coke in a receptacle 'adapted to receive an accumulating charge of .receptacle and supplying the resulting i receptacle to the said coke and'thereby coking said oil mixture in said receptacle, discharging the hot vapor mixture from the said coking receptacle into and beneath the surface of a liquid body of oil maintained at a temperature `not exceeding i 800 F. in a separate receptacle, supplying comprises vaporizing and cracking oil in thev vapor phase passing the -hot vapor mixture from the vapor phase cracking operation, before the temperature of the said vapor mixture falls below 950 F., in intimate contact -With a heavy hydrocarbon liquid oil mixture to be reduced to coke in a receptacle adapted to receive an accumulating charge kof coke and thereby coking said oil mixture in said receptacle, discharging the hot vapor mixture from the said coking receptacle into and beneath the surface lof a liquid body of oil maintained atf atemperature not exceeding 750 F. in a separate, receptacle, supplying the oil to be reduced to coke to the said liquid body in the said separate receptacle and supplying the resulting liquid oil mixture from the liquid body in the said separate receptacle to the said coking receptacle, discharging a vapor mixture from the said separate receptacle and periodically 'discharging a coke product from the said coking receptacle.

5. In a combined oil vapor phase cracking and coking operation, the improvement which comprises vaporizing and cracking oil in the vapor phase supplying a stock of which 70% boils off Within a range not substantially exceeding F. under atmospheric pressure to .a vapor' phase cracking operation, passing' the hot vapor mixture from the vapor phase cracking operation, before the temperature of the said vapor mixture falls below 950 F.,

in intimate contact with a heavy hydrocarbon liquid oil mixture to4 be reduced" to coke in aA receptacle adapted to receive an accumulati ingy charge .pf coke and thereby coking said oil mixture lin vsaid receptacle, discharging the hot-vapor'mixture from the said coking receptacle into and beneath the surface of a liquid body of oil in asseparatejreceptacle,` supplying the oil to be-reduced to coker'to thesaidn liquid body inthe said separate` receptacle land supplying the resulting liquid n @combined oil .cracking and' coking operation, the improvement Which comp-rises passing an oil to be cracked through a heating conduit and heating this oil to a high cracking temperature therein, passing the hot oil products from the heating conduit, before the temperature of said hot oil products falls below 950 F., in intimate contact with a heavy hydrocarbon oil mixture to be reduced to coke in a receptacle adapted to receive an accumulating charge of coke and thereby coking said oil mixture in said'receptacle, discharging the hot vapor mixture passmg an oil to' be cracked through a heating conduit and heating this oil to a high cracking tem erature therein, passing the hot oil products iiom the heating conduit, before the temperature of said hot oil products falls `below 1050 F., in intimate contact with a heavy hydrocarbon oil mixture to be reduced to cokein a receptacle adapted to receive an accumulating charge of coke and therebycoking said oilmixture in said receptacle, discharging the hot vapor mixture from said coking receptacle into and beneath the surface ofa liquid body of oil in a separate refj l ceptacle,'supplying the oil to be reduced to coke to the said liquid body in the said separate receptacle and supplying the resulting liquid oil mixture from the liquid body in the said separate receptacle to the cokin receptacle, discharging a vapor mixture rom the said separate receptacle and periodically discharging a coke product from the said coking receptacle. i

8. In a combined oil cracking andcoking operation, the improvement' which comprises passing an oil to be cracked through a heating conduit and heating this oil to a high cracking temperature therein, passing the hot oil productsiroin the heating conduit, before Ithe, temperature of said hot oil products falls belovsi 950 F., in intimate contact with a heavy hydrocarbon oil 'mixture to be reduced tQ coke in. a receptacleadapted to receive an oil mixture from the liquid body in the said` aqcumulatmg Charge o coke and thereby vseparate receptacle to l'the said coking 'rei' ceptacle, discharging a vapor mixture from f ;the said separate'receptacle and periodically discharging ai` coke product from the said 'Lcolcingreceptacld coking said oil mixture in said receptacle,

disclia'rgin g the .hot vapor mixture from saidV coking receptacle into and beneath the sur, face' of a liquid bodyof oil maintained atjal temperature notvexceeding 800 F. in 'a separate receptacle, 'supplying thedoil be trie- 1qu1 d o y 1n e l, I .j

duced to coke vto the said 'iso said separated receptacle and supplying the resulting liquid oil mixture from the liquid body in the said separate receptacle to the coking receptacle, discharging a vapor mixture from the said separate receptacle and periodically discharging a coke product from the said coking receptacle.

9. In a combined oil cracking and coking operation, the improvement which comprises passing an oil to be cracked through a heating conduit and heating this oil to a high cracking temperature therein, passing the hot oil products from the heating conduit, before the temperature of said hot oil products falls below 950 F., in intimate contact with a heavy hydrocarbon oil mixture to be reduced to coke in a receptacle adapted to receive an accumulating charge ofcoke and thereby coking said oil mixture in said receptacle, discharging the hot vapor mixture from said cok-ing receptacle into and beneath the surface of a liquid body of oil maintained at a temperature not exceeding 750 F. in a separatel receptacle, supplying the oil to be reduced to coke to the said liquid body `in the said separate receptacle and supplying the resulting liquid oil mixture from the liquid body in the said separate receptacle to the coking receptacle, discharging a' vapor mixture from the said separate receptacle and periodically discharging a coke product from the said coking receptacle.

10.l In a combined oil cracking and coking operation, the

passing a hydrocarbon oil stock of which 70% boils off within a range not substantially l exceeding 30o F. under atmospheric pressure through a heating conduit and heating this oil to a high cracking temperature therein,

passing the hot oil products from the heating conduit. before the temperature of said hot oil products falls belowr 950 F., in intimate contact with a heavy hydrocarbon oil improvement which comprises' mixture to be reducedto coke in a receptacle adapted to receive an accumulating charge of coke and thereby coking said oil mixture in said receptacle, discharging the hot vapor mixture from said coking receptacle into and beneath.the surface of a liquid body of oil in a separate receptacle, supplying the oil to be reduced to coke to the said liquid body in the said separate receptacle and supplying the resulting liquid oil mixture from the liquid body in the said separate receptacle to the coking receptacle, discharging a vapor mixture from the said separate receptacle and periodically discharging a coke product from the said coking receptacle.

In testimony whereof I aiix my signature.

HARRY L. PELZER. 

